Continuous-belt drilling mud separation system

ABSTRACT

A continuous-belt drilling mud separation unit is removably mounted in a box-like housing disposed in the flow path of drilling mud or drilling fluids and is operated by a motor on the housing. The separation unit includes a generally rectangular frame, a tensioning system, and a wide continuous belt in the form of a mesh screen, chain, self-cleaning chain link belt, or combination chain link belt and wire mesh screen which extends around rollers or sprockets and is driven in a continuous loop moving along the longitudinal axis of the frame. As drilling mud or drilling fluids are conducted onto the moving belt, liquids and particles smaller than the openings in the belt pass through the openings and liquids and particles larger than the openings are transported on the moving belt and are discharged off of one end as the belt completes its path. The drilling mud separation system is installed upstream from conventional solids control equipment, such as shale shakers, and removes large amounts of large drill solids and gumbo from the drilling mud or drilling fluid prior to the drilling fluid or drill mud flowing to the conventional solids control equipment. By removing large drill solids and gumbo from the drilling mud or drilling fluid, the present apparatus improves the efficiency and performance and reduces the cost of operating and maintaining the conventional solids control equipment.

This application claims the benefit of prior provisional patentapplication Serial No. 60/016,863, filed May 6, 1996, which is fullyincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to drilling mud separation systems, andmore particularly to a drilling mud separation system which utilizes amoving continuous belt in the form of a screen, chain, self-cleaningchain link belt, or combination chain link belt and wire mesh screen toremove large drill solids and gumbo from the drilling mud or drillingfluid prior to the drilling fluid or drilling mud flowing toconventional solids control equipment.

2. Brief Description of the Prior Art

Effective solids control systems for controlling the solids in drillingmud has been a goal in the oilfield industry for many years. Varioushave been employed to give higher penetration rates, less contaminationof formations, lower mud costs, and less abrasives and sticky materialsin the mud system. The systems which are most effective requireexpensive and complicated machinery and require personnel to monitor andmaintain the machinery. Common apparatus used for mechanically removingsolids from drilling mud include shale shakers and vibratory screens,desanders, desilters, mud cleaners and centrifuges. Each piece ofequipment is limited to a range of various particle sizes andselectively reject undesirable solids and retain desirable solids in thedrilling fluid.

The shale shakers and mud cleaners employ a vibrating screen toselectively classify particles by size differences. The desander,desilter and centrifuge are usually located downstream from the shaleshakers and utilize centrifugal force and mass difference between thesolids density and liquid density for solids removal.

The initial removal step in most solids control systems is to conductthe drilling mud from the well directly to a shale shaker. Vibratingscreen shale shakers of the type used in the oil industry fall intothree general categories, as described below.

"Elliptical motion", or "unbalanced design" shakers have a downwardslope on the screen to transport cuttings across the screen and off thedischarge end. Optimum screening with these types of shakers is usuallyin the range of 30-40 mesh (400-600 microns), and they are prone tobearing failure.

"Circular motion", or "balanced design" shakers produce a balanced, orgenerally circular motion. The consistent, circular vibration allowssolids transport with the basket in a flat, horizontal orientation. Thistype of shaker usually has multiple decks to split the solids load andallow the use of finer mesh screens in the range of 80-100 mesh (150-180microns).

"Linear motion", or "straight-line motion" shakers produce a generallystraight motion. This motion is developed by a pair of eccentric shaftsrotating in opposite directions. Linear motion shakers provide superiorcutting conveyance and are able to operate at uphill slope which allowsthe use of 200 mesh screens (77 microns).

Most prior art shakers tend to force the cuttings upward from the screensurface and as they continue upward the screen travels down, and as thecuttings fall downward, the screen travels upward and strikes thecuttings which chips small pieces off and creates very fine cuttingsthat are extremely difficult to remove. Shale shakers are prone to shortscreen life and their vibratory action tends to drive the cuttings intothe screen and leads to screen "blinding" resulting in loss of fluidacross the screen. "Blinding" is known as the phenomenon where near-sizeparticles plug the screen or the screen becomes coated with stickyparticles.

The present invention is not a replacement for the conventional solidscontrol equipment but instead is installed upstream from theconventional solids control equipment and removes large amounts of largedrill solids and gumbo from the drilling mud or drilling fluid prior tothe drilling fluid or drill mud flowing to the conventional solidscontrol equipment such as shale shakers. The present apparatus utilizesa separation unit removably installed in a box-like housing whichreceives the drilling mud or drilling fluid from the well separates thelarge drill solids and gumbo by utilizing a moving continuous belt inthe form of a screen, chain, self-cleaning chain link belt, orcombination chain link belt and wire mesh screen which moves in ancontinuous loop. By removing large drill solids and gumbo from thedrilling mud or drilling fluid, the present apparatus improves theefficiency and performance and reduces the cost of operating andmaintaining the conventional solids control equipment. Removablymounting the separation unit in the box-like housing allows areplacement separation unit to be easily and quickly installed so thatoperations may continue while the removed separation unit is repaired.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide acontinuous-belt drilling mud separation unit which is removably mountedin a box-like housing disposed in the flow path of drilling mud ordrilling fluids upstream from conventional solids control equipment,such as shale shakers, and removes large amounts of large drill solidsand gumbo from the drilling mud or drilling fluid prior to the drillingfluid or drill mud flowing to the conventional solids control equipment.

It is another object of this invention to provide a continuous-beltdrilling mud separation unit which is easily and quickly removed from abox-like housing to allow a replacement separation unit to be easily andquickly installed so that operations may continue while the removedseparation unit is repaired.

Another object of this invention is to provide a box-like housing whichremovably receives, supports and operates a continuous-belt drilling mudseparation unit installed therein.

Another object of this invention is to provide a continuous-beltdrilling mud separation unit having a tensioning mechanism for applyingand maintaining tension in the continuous belt.

Another object of this invention is to provide a continuous-beltdrilling mud separation unit having a wide continuous belt in the formof a mesh screen, chain, self-cleaning chain link belt, or combinationchain link belt and wire mesh screen which extends around rollers orsprockets and is driven in a continuous loop moving along thelongitudinal axis of the frame.

Another object of this invention is to provide a continuous-beltdrilling mud separation unit having a wide continuous belt containing aplurality of openings moving in a continuous loop whereby liquids andparticles smaller than the openings in the belt pass through theopenings and liquids and particles larger than the openings aretransported on the moving belt and are discharged off of one end as theforamanous belt completes its path.

A further object of this invention is to provide a continuous-beltdrilling mud separation system upstream from conventional solids controlequipment to remove large drill solids and gumbo from the drilling mudor drilling fluid and thereby improve the efficiency and performance andreduce the cost of operating and maintaining the conventional solidscontrol equipment.

A still further object of this invention is to provide a continuous-beltdrilling mud separation system which is simple in construction,inexpensive to manufacture and operate and is rugged and reliable inoperation.

Other objects of the invention will become apparent from time to timethroughout the specification and claims as hereinafter related.

The above noted objects and other objects of the invention areaccomplished by a continuous-belt drilling mud separation unit removablymounted in a box-like housing disposed in the flow path of drilling mudor drilling fluids which is operated by a motor on the housing. Theseparation unit includes a generally rectangular frame, a tensioningsystem, and a wide continuous belt in the form of a mesh screen, chain,self-cleaning chain link belt, or combination chain link belt and wiremesh screen which extends around rollers or sprockets and is driven in acontinuous loop moving along the longitudinal axis of the frame. Asdrilling mud or drilling fluids are conducted onto the moving belt,liquids and particles smaller than the openings in the belt pass throughthe openings and liquids and particles larger than the openings aretransported on the moving belt and are discharged off of one end as thebelt completes its path. The drilling mud separation system is installedupstream from conventional solids control equipment, such as shaleshakers, and removes large amounts of large drill solids and gumbo fromthe drilling mud or drilling fluid prior to the drilling fluid or drillmud flowing to the conventional solids control equipment. By removinglarge drill solids and gumbo from the drilling mud or drilling fluid,the present apparatus improves the efficiency and performance andreduces the cost of operating and maintaining the conventional solidscontrol equipment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded isometric view of the separation unit of thedrilling mud and gumbo separation system in accordance with the presentinvention.

FIG. 2 is an isometric view in the assembled condition of an embodimentof the separation unit having a moving screen.

FIG. 3 is an isometric view in the assembled condition of an embodimentof the separation unit having a moving chain.

FIG. 4 is an isometric view of a toothed drive roller and self-cleaningchain link belt for use in the separation unit.

FIG. 5 is a side elevation view of a portion of the self-cleaning chainlink belt and toothed drive roller arrangement.

FIG. 6 is an isometric view of the toothed drive roller and acombination self-cleaning chain link belt and wire mesh screen for usein the separation unit.

FIG. 7 is a side elevation of the receptacle or box-like housing unit ofthe system in which the separation unit is mounted.

FIG. 8 is a top plan view of the box-like housing unit.

FIG. 9 is a front elevation of the box-like housing unit.

FIG. 10 is a rear elevation of the box-like housing unit.

FIG. 11 is an isometric view of the box-like housing unit shown from thefront end.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The apparatus of the present invention utilizes a moving continuous beltin the form of a screen, chain, self-cleaning chain link belt, orcombination chain link belt and wire mesh screen to remove large drillsolids and gumbo from the drilling mud or drilling fluid prior to thedrilling fluid or drill mud flowing to conventional solids controlequipment such as shale shakers to remove large amounts of large drillsolids and gumbo and lessen the stoppage of flow of drilling mud anddrilling fluids in the flow lines and thereby improve the performanceand reduce the cost of drilling operations.

Referring to the drawings by numerals of reference, the mud separationsystem in accordance with the present invention includes; (1) aseparation unit 10 depicted in FIGS. 1-6 which is installed in (2) areceptacle or box-like housing 30 depicted in FIGS. 7-11. The separationunit 10 includes an outer frame, inner front and rear frames, atensioning system, a drive system, and a moving continuous belt in theform of a screen, chain, self-cleaning chain link belt or combinationchain link belt and wire mesh screen, described hereinafter. Thereceptacle or box-like housing 30 is mounted in the flow path of thedrilling mud or drilling fluids on a drilling rig and serves to operatethe separation unit or units 10 to separate gumbo and solids fromdrilling fluids or drilling muds obtained from a well bore.

Referring now to FIGS. 1-3, the separation unit 10 of the apparatus hasa generally rectangular outer frame assembly 11 formed of C-shapedchannel members that supports an inner front frame assembly 12, an innerrear frame assembly 26, and other components. The separation unit 10 isshown in an unassembled condition in FIG. 1, and in an assembledcondition in FIGS. 2 and 3. FIG. 2 shows an embodiment of the separationunit 10 having a moving continuous screen belt 17A, and FIG. 3 shows anembodiment having a moving continuous chain belt 17B. The same numeralsof reference are used in both embodiments to designate the componentscommon to both. FIGS. 4-6 show a toothed drive roller and self-cleaningcontinuous chain link belt and combination chain link belt and wire meshscreen modification.

The inner front frame assembly 12 is a generally U-shaped configurationformed of a pair of laterally opposed rectangular side plate members 12Awith a transverse rectangular crossmember plate 12B secured between theinner facing ends of the side plates. Front bearings 13 are mounted atthe outer ends of the opposed plates 12A (FIGS. 2 and 3). The U-shapedinner front frame assembly 12 carrying the front bearings 13 is fixedlyconnected to the front end of the outer frame assembly 11 by spacerplates 19. A front drive axle 14 is journalled in the front bearings 13and its outer ends extend through the front bearings 13 and through theouter frame assembly 11 to receive a drive sheave 15 on either the rightor left side of the outer frame 11. Thus, the drive sheave 15 can belocated on either the left or the right side of the outer frame 11.

In the embodiment of FIG. 2, a drive roller 42 is connected to the frontaxle assembly 14 to drive a moving continuous screen belt 17A, and inthe embodiment of FIG. 3, drive sprockets 16 are attached to the frontaxle assembly 14 to drive a moving continuous chain belt 17B.

Lifting eyes 18 are secured to the front end of the outer frame assembly11 to lift and move the separation unit 10 as required. The inner frontframe assembly 12, spacer plates 19, and the front bearings 13 areattached to the outer frame assembly 11 to make the front of theseparation unit 10 rigid. Holes 20 are located on the front of the outerframe assembly 11 to attach the inner front frame assembly 12, frontbearings 13 and spacer plates 19.

As best seen in FIG. 1, tensioning cylinders 21 are mounted on the innerfront frame assembly 12 to create and maintain tension force on themoving screen 17A or chain 17B. Lines 22 connect the tensioningcylinders 21 to a reservoir 23 which is mounted on the transversecrossmember 12B of the inner front frame assembly 12. The reservoir 23contains a fluid medium (air or hydraulic) with which to operate thetensioning cylinders 21. A line 24 connected to the reservoir 23 extendsthrough a mounting plate 25 attached to the side of the outer frameassembly 11. An air or hydraulic supply line from the rig is connectedto the line 24 which in turn activates the tensioning cylinders 21.

The inner rear frame assembly 26 is a generally H-shaped configurationformed of a pair of laterally opposed rectangular side plate members 26Awith a transverse rectangular crossmember plate 26B secured between theside plates and laterally opposed end plates 26C secured to the frontends of the side plates. Rear bearings 27 are mounted at the rear endsof the opposed plates 26A (FIGS. 2 and 3). The H-shaped inner rear frameassembly 26 carrying the rear bearings 27 is not rigidly connected toouter frame assembly. Instead, the inner rear frame assembly 26 isslidably received in the C-shaped side channels of the outer frame 11.

A rear axle 28 is journalled in the rear bearings 27. In the embodimentof FIG. 2, an elongate single roller 29A is connected to the rear axle28 over which the moving screen belt 17A passes, and in the embodimentof FIG. 3, a pair of laterally opposed rollers 29B are attached to therear axle 28 over which the chain belt 17B passes.

The outer ends of the piston rods 21A of the tensioning cylinders 21 areconnected to the end plates 26C at the front ends of the side plates 26Bof the inner rear frame assembly 26. The inner rear frame assembly 26and rear rollers 29A, 29B, are moved along the C-shaped side channels ofthe outer frame 11 relative to the outer frame by the tensioningcylinders 21.

In the embodiment of FIG. 2, the moving continuous screen belt 17A is inthe form of an endless loop and passes around the front drive roller 42and rear roller 29A. In the embodiment of FIG. 3, the continuous chainbelt 17B is formed of a plurality of transverse parallel spaced rodmembers 50 defining openings therebetween and having jointed links 17Dat each end. The links 17D are interconnected such that the transverserod members 50 are in the form of an endless loop. The links 17C of thechain 17B engage the teeth of the front drive sprockets 16 and pass overthe laterally opposed rear rollers 29B.

FIG. 4 shows an alternate embodiment of the front drive roller 42A whichis used to drive a continuous self-cleaning chain link belt 17C. Thefront drive roller 42A is similar to the front drive roller 42 describedabove with reference to FIG. 2, but has a plurality of longitudinallyextending circumferentially spaced rows of radially extending teeth 42B.The self-cleaning chain link belt 17C is a wide endless loop belt formedof a plurality of adjacent jointed chain links 17D hingedly connectedtogether by a plurality of parallel spaced transversely extending rods17E. The endless loop chain link belt 17C passes around the front driveroller 42A and rear roller 29A (shown in FIG. 2). The jointed chainlinks 17D are sized and spaced to receive and engage the teeth 42B ofthe front drive roller 42A. As shown in FIG. 5, the teeth 42B are ofsufficient length to protrude slightly beyond the outer surface of thelinks 17D as they pass around the front drive roller 42A. The toothedfront drive roller 42A and chain link belt 17C arrangement isparticularly useful in removing gumbo and other large solids which mayotherwise stick in the openings of the links and clog the belt. As shownsomewhat schematically in FIG. 5, a rectangular wiper blade W formed ofresilient elastomeric material sandwiched between two rectangular metalstraps may be secured transversely across the front of the frame to wipethe outer surface of the chain link belt 17C as it passes around thedrive roller 42A.

FIG. 6 shows a modification of the toothed front drive roller 42A andcontinuous self-cleaning chain link belt 17C arrangement. In thismodification the front drive roller 42A and chain link belt 17C is thesame as described above with reference to FIGS. 4 and 5. In thisarrangement, an endless loop screen belt 17F formed of wire mesh isinstalled on the outer surface of the chain link belt 17C. The endlessloop chain link belt 17C and screen 17F move together and pass aroundthe front drive roller 42A and rear roller 29A (shown in FIG. 2), andthe jointed chain links 17D receive and engage the teeth 42B of thefront drive roller 42A, as described above.

It should be understood from the foregoing that the inner rear frameassembly 26 carrying the rear rollers 29A, 29B slides relative to theouter frame 11 and inner front frame assembly 12 upon extension orretraction of the piston rods 21A of the tensioning cylinders 21. Whenthe piston rods 21A are extended the inner rear frame assembly 26 andrear rollers 29A, 29B move rearwardly to apply and maintain tension inthe moving screen 17A, chain 17B, chain link belt 17C, or combinationchain link belt 17C and screen 17F.

A pair of laterally opposed parallel elongate rectangular guide/supportbars 43 are connected at one end to the crossmember 26B of the innerrear frame assembly 26 and extend forward toward the front of theseparation unit 10 and over the crossmember 12B of the inner front frameassembly 12 to support the moving screen 17A, chain 17B, chain link belt17C, or combination chain link belt 17C and screen 17F. Theguide/support bars 43 move with the inner rear frame assembly 26relative to the outer frame 11 as tension is applied or relaxed by thetensioning cylinders 21.

A pair of elongate flat guard rails 41 are mounted at the top ends ofthe C-shaped channels of the outer frame 11 after the moving screen 17A,chain 17B, chain link belt 17C, or combination chain link belt 17C andscreen 17F is installed. The guard rails 41 extend inwardly from thesides of the outer frame assembly 11 over the lateral edges of themoving screen 17A, chain 17B, chain link belt 17C, or combination chainlink belt 17C and screen 17F and forwardly over the drive sprockets 16or the lateral ends of the drive roller 42 or 42A.

The moving screen 17A, chain 17B, chain link belt 17C, or combinationchain link belt 17C and screen 17F of the separation unit 10 is drivenby a variable or fixed speed external motor 40 mounted in the box-likehousing 30 which is releasably connected 40 to the drive sheave 15 onthe outwardly extended end of the drive shaft 14.

As briefly stated above, the separation unit 10 is installed in thereceptacle or box-like housing 30 depicted in FIGS. 7-11 which ismounted in the flow path of the drilling mud or drilling fluids on adrilling rig and serves to operate the separation unit or units 10 toseparate solids from drilling fluids or drilling muds obtained from awell bore.

Referring now to FIGS. 7-11, the receptacle or box-like housing 30(hereafter referred to as box 30) is mounted on the rig through whichthe drilling mud or drilling fluids along with materials to be separatedflow through from the well bore. The box 30 is mounted to the drillingrig floor by conventional supports and attachments to the floor or maybe suspended from overhead or by other means that may be applied byworkmen at each work location. The box 30 has laterally opposed sidewalls 32 connected to a pair of opposed end walls 33 and 34; end wall 33being the front (discharge end), and end wall 34 being the back (inletend) of the box.

A pair of elongate laterally opposed parallel rails 31 are mounted onthe inside of the opposing side walls 32 at a fixed distance apart toallow the separation unit 10 to be slidably received and supported inthe box 30. The parallel rails 31 are fixed in the box 30 at an anglethat is preferably 70° to 80° from vertical measuring from the back wall34 (inlet end) of the box. It should be understood that the separationunit 10 can function satisfactorily at other angles other than thepreferred degrees stated above.

The box 30 is configured to facilitate the installation and removal ofthe separation unit 10 through the front end of the box and allow thefront drive axle 14 and drive sheave 15 (FIGS. 2 and 3) of theseparation unit 10 to extend through the side of the box. Removablymounting the separation unit in the box-like housing allows areplacement separation unit to be easily and quickly installed in thebox so that operations may continue while the removed separation unit isrepaired.

The box 30 has a mounting flange or bracket 41 on one or both sides onwhich a variable or fixed speed drive motor 40 is mounted to drive theseparation unit 10. The external drive motor 40 can be located on eitherside of the box 30 as dictated by the installation of the box 30 at aparticular location. The external drive motor 40 may be electrically,hydraulically, or pneumatically powered. The drive sheave 15 of theseparation unit 10 is rotated by a belt (not shown) that is driven bythe motor 40. Thus, the front drive axle 14 and the moving screen 17A,chain 17B, chain link belt 17C, or combination chain link belt 17C andscreen 17F of the separation unit 10, can be driven from the left orright side of the box 30.

The box 30 has a horizontal ledge or shelf 35 which extends inwardly adistance from the back wall 34 (inlet end) to disperse the drilling mudor drilling fluid along with the material to be separated across theseparation unit 10 which is supported on the rails 31. The drilling mudor drilling fluid enters the box 30 through an opening 36 in the backwall 34 (inlet end) of the box or it can be directed over the open topend of the box 30 by the existing flow line (which is part of the rig)onto the ledge or shelf 35. The box 30 may be provided with a dischargeoutlet 37 in the bottom of the box, an outlet 38 on either or both sidesof the box, or an outlet 39 in the front wall of the box.

Drilling mud or drilling fluids are obtained from the well bore alongwith drill solids to be removed from the drilling mud or drilling fluidsby mechanical or other means. The drilling mud or drilling fluid flowsthrough, or is circulated through, the existing flowline and into thebox 30. The ledge or shelf 35 evens or smooths the flow onto the movingscreen 17A, chain 17B, chain link belt 17C, or combination chain linkbelt 17C and screen 17F.

The moving screen 17A, chain 17B, chain link belt 17C, or combinationchain link belt 17C and screen 17F is rotated around the drive roller42, 42A, or drive sprockets 16 in an endless loop and passes underneaththe separation unit 10 toward the rear roller 29A, 29B. The movingscreen 17A, chain 17B, chain link belt 17C, or combination chain linkbelt 17C and screen 17F then passes around the rear roller 29 and movesunderneath the flow of drilling mud or drilling fluid from the well borewhere large solids and gumbo from the well bore are deposited on themoving screen 17A, chain 17B, chain link belt 17C, or combination chainlink belt 17C and screen 17F. The moving screen 17A, chain 17B, chainlink belt 17C, or combination chain link belt 17C and screen 17Fcontinues forward movement across the guide/support bars 43 to the frontdrive roller 42, 42A, or drive sprocket 16.

As the drilling mud or drilling fluids along with the drill solids andgumbo to be separated flow across the moving screen 17A, chain 17B,chain link belt 17C, or combination chain link belt 17C and screen 17F,the liquid part of the drilling mud or drilling fluid along with smallerparticles of drill solids fall through the openings of the moving screen17A, chain 17B, chain link belt 17C, or combination chain link belt 17Cand screen 17F into the lower part of the box 30 then exits the box 30through the discharge outlets 37, 38, or 39 in the box. Larger drillsolids and gumbo are caught on the moving screen 17A, chain 17B, chainlink belt 17C, or combination chain link belt 17C and screen 17F and aretransported to the front of the separation unit 10.

As the moving screen 17A, chain 17B, chain link belt 17C, or combinationchain link belt 17C and screen 17F passes under the front drive sprocket16 or front drive roller 42 or 42A, the large drill solids and gumbo aredischarged off the moving screen 17A, chain 17B, chain link belt 17C, orcombination chain link belt 17C and screen 17F into a suitable dischargereceptacle, pipe, conveyor, or other means as may be provided at eachunit location. In the toothed roller 42A and self-cleaning chain linkbelt 17C, or combination chain link belt 17C and screen 17F arrangement,the teeth 42B of the drive roller 42A are received in the jointed chainlinks 17D and protrude therethrough to dislodge and remove gumbo andother large solids which may be stuck in the openings of the links toclean and unclog the belt as the links 17D pass around the front driveroller.

It should be understood that as drilling conditions vary such as size ofhole drilled, drilling rate, type of drilling fluids or drilling mudused, type of formation drilled, volume of drilling mud or drillingfluids circulated per unit of time such as gallons per minute, themoving screen 17A, chain 17B, chain link belt 17C, or combination chainlink belt 17C and screen 17F may be varied in size of spacing betweenlinks, joints, mesh of screen or chain along with drive sprockets and/ordrive rollers designed for each particular size or type of screen orchain, or the length of the separation assembly may be increased ordecreased as well as the width.

The present invention utilizing a moving screen, chain, chain link beltor combination chain link belt and screen to remove large drill solidsand gumbo from the drilling mud or drilling fluid prior to the drillingfluid or drill mud flowing to conventional solids control equipment;i.e. shale shakers, has resulted in better performance of theconventional solids control equipment. The removal of large amounts oflarge drill solids and gumbo lessens the stoppage of flow of drillingmud and drilling fluids in the flow lines and therefore improves theperformance and reduces the cost of drilling operations.

While this invention has been described fully and completely withspecial emphasis upon preferred embodiments, it should be understoodthat within the scope of the appended claims the invention may bepracticed otherwise than as specifically described herein.

I claim:
 1. In a drilling mud separation system wherein drilling fluidand drilling mud are conducted from a well bore to solids controlequipment such as shale shakers and vibratory screens; a drilling mudseparation unit for separating large particles from said drilling fluidsand drilling mud, comprising:a generally rectangular frame having afront frame member having a front end, a back end, and laterally opposedsides connected by a transverse crossmember; a rear frame member havinga front end, a back end, and laterally opposed sides connected by atransverse crossmember; said front and rear frame members beingtelescopically connected for sliding movement relative to one anotheralong a longitudinal axis; rotary drive means rotatably mounted on saidfront frame member front end to rotate about an axis transverse to thelongitudinal axis of said generally rectangular frame; rotary meansrotatably mounted on said rear frame member back end to rotate about anaxis transverse to the longitudinal axis of said generally rectangularframe; a continuous belt containing a plurality of openings extendingaround said front rotary drive means and said rear rotary means in acontinuous loop, said continuous belt engaged with said rotary drivemeans and driven thereby in a continuous path moving along thelongitudinal axis of said generally rectangular frame; tensioning meansconnected between said front and rear frame members for moving saidframe members relative to one another and thereby moving said rotarydrive means and said rotary means relative to one another along thelongitudinal axis of said frame to adjust tension in said continuousbelt; whereby drilling fluid and drilling mud are conducted from thewell bore and onto said moving continuous belt and liquids and particlessmaller than the openings in said continuous belt pass through theopenings in said continuous belt and liquids and particles larger thansaid openings are transported on said continuous belt and are dischargedas said continuous belt passes around said rotary drive means.
 2. Thedrilling mud separation unit according to claim 1 whereinsaid rotarydrive means comprises a first cylindrical roller extending transverselyacross said frame front end and having an axle at each end journalled insaid frame opposed sides; said rotary means comprises a secondcylindrical roller extending transversely across said frame back end andhaving an axle at each end journalled in said frame opposed sides; andsaid continuous belt comprises a mesh screen belt looped around saidfirst and second cylindrical rollers in a continuous loop and tensionedtherebetween to be driven thereby in a continuous path moving along thelongitudinal axis of said generally rectangular frame.
 3. The drillingmud separation unit according to claim 1 whereinsaid rotary drive meanscomprises a pair of laterally spaced toothed sprockets fixed to an axleextending transversely across said frame front end and journalled insaid frame opposed sides; said rotary means comprises a pair oflaterally spaced rollers fixed to an axle extending transversely acrosssaid frame back end and journalled in said frame opposed sides; saidcontinuous belt comprises a chain belt formed of plurality of transverseparallel spaced rods with openings therebetween having interconnectedjointed links at each end which are looped around said laterally spacedtoothed sprockets and said laterally spaced rollers in a continuousloop; and said interconnected jointed links being engaged on saidtoothed sprockets to be driven thereby such that said plurality oftransverse parallel spaced rods move in a continuous path along thelongitudinal axis of said generally rectangular frame.
 4. The drillingmud separation unit according to claim 1 whereinsaid tensioning meanscomprises at least one fluid cylinder having a piston rod extendingtherefrom connected with a source of fluid under pressure through valvemeans to extend and retract said piston rod; and said at least one fluidcylinder connected between said front and rear frame members to movesaid frame members relative to one another to apply and maintain tensionin said continuous belt.